In the example “This primer focuses on the parts only humans can do well”
doesn't it make more sense adding the relative pronoun “that”,
as it narrows down the precision, like for example
“This primer focuses on the parts that only humans can do well”?
I'm looking for a mental model telling me exactly that I'm referring to “parts humans can do well”, and not to any other parts that we may delegate to, for example, Ai.
Here, using the pronoun “that” improves the context for me.
The omission of the relative pronoun makes me stop for a split of a second to connect object “parts” to the reduced relative clause “humans can do well”. It sounds short and concise, but there is a cognitive price.
You’ve hit on a concept called syntactic processing or “garden-pathing.”
When you omit the relative pronoun, the reader's brain has to momentarily hold the word “parts” in limbo until “humans can do well” provides the context.
Adding “that” acts as a functional signpost.
It signals immediately that a description is coming,
which reduces the “cognitive load” you're feeling.
If your goal is absolute clarity and minimizing the reader's “stop-and-think” time,
keeping “that” is actually the better move.
Efficiency isn't just about fewer words; it's about how fast the brain can digest the meaning.
Using the relative pronoun is what's called “signpost” logic.
The feeling of a “split second” delay is grammatically justified.
In a standard relative clause, the word “that” acts as a functional marker that tells the brain:
“Stop treating the previous noun as a finished thought;
a description is starting”.
Without it, your brain initially processes “parts”
and “humans” as two separate nouns side-by-side.
It only realizes they are connected once it hits the verb “do,”
at which point it has to go back and re-categorize “humans can do well” as a description of “parts”.